In the patented art, the U.S. Pat. No. 3,111,808 to Fritz discloses a single-stroke actuator in which a piston is driven by detonation of an explosive charge, from a retracted position to a projected position in which it is held against return movement by penetration of a sharp edge at the trailing end of the piston into the cylinder wall under the reactive load (e.g. air pressure) tending to thrust the piston back into the cylinder. An actuator or propelling device having an explosive charge-propelled piston is also disclosed in Barr U.S. Pat. No. 3,119,302. Other patents disclosing devices powered by explosive charges are: Gross U.S. Pat. No. 2,742,697; Stupian U.S. Pat. No. 2,897,799; Bohl U.S. Pat. No. 2,924,147; and Stott U.S. Pat. No. 2,942,818.